Rotating control head



March 16, 1965 T. A. ovERBY 3,173,502

ROTATING CONTROL HEAD March 16, 1965 T. A. ovERBY ROTATING CONTROL. HEAD2 Sheets-Sheet 2 Filed Oct. 31. 1960 IN V EN TOR. TERRY OVERBY UnitedStates Patent O 3,173,502 ROTATING CONTROL HEAD Terry A. Overby, 325 W.Delaware, Nowata, Okla. Filed Oct. 31, 1960, Ser. No. 66,304 Claims.(Cl. 17E-210) This invention relates to improvements in well drillingapparatus, and more particularly, but not by way of limitation, to anovel rotary fluid control head.

One of the more successful advancements in well drilling in recent yearshas been the use of air or gas as the circulating medium. The use of airor gas has been employed mainly where there has been a possibility ofinjury to the producing zone by liquid penetration or where there hasbeen a loss of circulation. Other reasons for the use of air or gas havebeen to provide greater drilling speed and longer bit life. However,this new well drilling procedure has been subject to certain problems.It has` been found that it is necessary to provide etiicient sealsaround the rotating drill string and other portions of the well drillingapparatus to preclude any air leakage during the drilling operationsince air or gas escape much more easily than Ia liquid and it isessential that there be no loss in pressure. Also, since it is necessaryto occasionally change the drill bit to insure an optimum drillingspeed, the sealing structure used must be readily disassembled to permitthe changing of the bit without undue delay of the drilling operation.The sealing structure must be readily adaptable to the use of a liquidas the circulating fluid, as well as air or gas, since during thedrilling of a well bore it may become necessary to change from one fluidto another.

The present invention contemplates a novel rotary control fhead whichprovides an efcient static seal between the drill stem and a portion ofthe control head rotating simultaneously therewith. An efhcient dynamicseal is also provided between the stationary and rotating portions ofthe control head -to preclude fluid leakage therethrough, regardless ofWhether liquid mud or air is utilized as the circulating fluid. Therotary control head may be partially disassembled during the welldrilling operation to service or replace the drill bit as thecircumstances may require without the necessity of completelydisassembling the control head or disturbing the set up of the rotarytable. A fluid seal is also provided between the control head and thecasings positioned in `the well bore so that all possibilities of fluidleakage are substantially precluded, since it is mandatory that a-control head utilized in air drilling be substantially leak proof.

An important object of this invention is to provide a novel control headparticularly designed and constructed to efficiently pack off a rotatingdrill string during a well drilling operation.

Another object of this invention is to provide a novel control lheadwhich provides an efficient static seal between a rotating drill stringand the rotary portion of the control head.

A further object of this invention is to provide a novel control headwhich provides an efficient dynamic seal between the stationary androtating portions of said control head.

A still further object of this invention is to provide a control headwhich efficiently packs off the control head from the well casing.

And yet another object of this invention is to provide a control headwhich permits a drill bit depending from a drill stem to be easilyserviced without completely disassem'bling Iand removing the controlhead from a derrick structure.

And a still further object of this invention is to provide a controlhead that is simple and inexpensive in construction and which is ofgreat utility in both large and small applications.

3,173,502 Patented Mar. 16, 1965 ICC Other objects and advantages of theinvention will be evident from the following detailed description, readin conjunction with the accompanying drawings, which i1- lustrate myinvention.

In the drawings:

FIGURE 1 is a side elevational view of the novel fluid control head.

FIGURE 2 is a longitudinal sectional view of the control head shown inFIG. l.

FIGURE 3 is a longitudinal section depicting a modification of the novelcontrol head.

FIGURE 4 is a sectional View taken along line 4--4 of FIG. 3.

FIGURE 5 is van enlarged sectional elevational view of a portion of thecontrol head device, partly in section, and particularly depicting adrill stem and drill bit in yassociation therewith.

Referring in detail to the drawings, and in particular fto FIG. 2,reference character 10 generally designates a novel rotary fluid controlhead preferably of a substantially tubular conguration. The control head10 comprises a tubular body member 14 provided with outwardly extendingflanges 16 and 18 secured to the opposed ends thereof. A sleeve member20 `having an outwardly extending flange 22 provided on its lower end isdisposed immediately adjacent to the upper flange 16 of the tubular body14. The upper flange 16 of the tubula-r body 14 is secured to the lowerflange 22 of sleeve 20 in any well known manner, although ange 16 ispreferably secured to flange 22 by any suitable connection members 21which permit the flanges 16 and 22 to be quickly disengaged when it isso desired. The connection members 21 may be suitable wedge pins and aresecured to the body 14 by a ychain 23 to preclude any accidental lossthereof in the disengaged position of the pins.

A plurality of outwardly extending flanges or lugs 24 are provided ronthe upper portion of the sleeve member 20 so that the sleeve 20 may besuspended from the stationary members 26 (shown in dotted lines in FIG.2) by any suitable means, such as hooks or hangersI 27 (FIG. l). Themembers 26 are preferably a portion of the substructure of the welldrilling rig (not shown) and always rem-ain stationary, regardless oftherotation of the rotary table or the drill string. The tubular body 14 isconnected with the support member 26 and thus is a stationary portion ofthe rotary control head 10.

The tubular member 2@ is further provided at its upper portion with aninwardly extending circumferential shoulder 2S which cooperates with asleeve 30 extending through the central bore 32 of the sleeve 20 todefine an annular -cavity 34 therebetween. The sleeve 30 rotates withinthe stationary sleeve 20 during the drilling operation, as will behereinafter set forth. A plurality of suitable annular sealing rings 36,preferably chevron rings, or the like, but not limited thereto, aredisposed in the cavity 34 to provide a dynamic seal between therotatable sleeve 30 and the router tubular member 20. An annularretaining ring 38 is threadedly secured to the inner bore 32 of thesleeve 20 at the lower portion thereof to support the chevron seals 36within the sleeve cavity 34 and to position the seals 36 therein so thatthe seals Contact ythe outer periphery of the rotatable tubular member3G withan optimum sealing pressure. It is understood that although theseals 36 lare shown as being chevron sealing rings, applicants novelrotary control head is not restricted to the specific use tof chevronsealing rings and another suitable packing could be substitutedtherefor. A radial passageway or port 40 is provided in the sleeve 2t)to receive a suitable lubricant fitting 42 whereby a suitable lubricantof any Well known ltype may be directed into the chamber 34 forlubrication of the 4sealing rings of packing 36. It is preferable thatthe lubricant comprise an oil that is supplied under pressure.

A sleeve member 46 having an outwardly extending flange 48 on its upperportion is positioned below and adjacent to the lower flange 1S of thebody 14 in order that the flange 48 may be secured 'to the flange 18 inany ell known manner, preferably in the manner utilized in theconnection of the flange 16 of sleeve 14 and flange 22 ofsleeve 2t). Thesleeve 14 is provided with an aperture 47 to provide communication witha tubular member 50 secured to the outer periphery of the sleeve 14around the aperture in order that a return fluid flow from the well boremay be directed through the aperture 47 into the tube 50 for dischargeto the slush pits, as will be hereinafter set forth.

The rotatable sleeve is secured at its upper portion to a drive bushing52 in any well known manner, such as welding or the like, but notlimited thereto. The drive bushing 52 is connected in any Well knownmanner to a rotary table 54 (shown in dotted lines in FlG. 2) providedon the substructure of a drilling derrick (not shown). The rotation ofthe rotary table 54 is imparted to the rotatable sleeve 30 through thedrive bushing 52, as is well known. The drive bushing 52 and rotarytable 54 are shown only generally since they do not constitute anessential portion of applicants invention and can be construed inaccordance with general design procedures. VThe rotatable tubular member30 has a sleeve member 56 (FIG. 2) threadcdly secured to the lowermostportien thereof for a purpose to be hereinafter set forth. The vsleevemember 56 extends divergingly outward from the lower portion of thesleeve 30 whereby the diameter of the inner bore of the sleeve 56 isgreater at its lower than at its upper portion. A circumferentialshoulder or Aflange SSextends radially outwardly from the lower portionof the sleeve 56 and is provided with an annular concave recess 60 onthe bottom portion thereof for receiving a sealing member or stripper62. The sealing member 62 is preferably of a substantially circularconguration and is constructed of a suitable resilient or flexiblematerial, such as neoprene, rubber or Ithe like, and is provided with asubstantially circular bead 64 formed on the outer edge thereofcomplementary to the groove 69 of the flange 58. The upper portion ofthe bead 64 is positioned within the complementary recess "66 of theflange 58 and an annular supporting ring 66 having a similarcomplementary recess 68 is positioned against the bottom portion of thering 62 so that the resilient member 62 is clamped therebetween. Aplurality of bolts 70 or other sealing means extend through the flange58 of the sleeve 56 and the supporting ring 66 for securing Athe sealingmember 62 securely in position at the lower portion of the sleeve 56. Acentral bore or aperture 72 is provided in the resilient member 62 inorder that a drill stem or kelly 73 may be extended therethrough, as iswell known. The diameter of the bore 72 is sufficiently smaller than theouter diameter of the drill string whereby a tight static seal may beprovided between the drill string and the sealing member 62 tosubstantially preclude any leakage of circulating fluid therebetween.The drill string is secured to the kelly in any well known manner forrotation therewith as is the usual practice in the drilling of a Wellbore.

The seal member 62 is shown herein as being a design which efficientlyseals around any kelly or drill stem 73 passing therethrough and thatallows for flexing either upwardly or downwardly as the drill stem ismoved relative thereto to preclude rupturing of the seal member.However, it is understood that although the stripper 62 is a preferredembodiment, the control head depicted herein is not restricted to aspecific use thereof and conditions may be encountered which deem itadvisable to use another stripper of any well known type. It is alsoconsidered to be within the scope of this invention to secure a secondstripper member (not shown) of suitable design to the bottom portion ofthe ring 66 to preclude cuttings from the well bore contacting thestripper 62 and to enhance the sealing properties thereof.

The drill stem 73 normally extends downwardly through the sleeve 36, thestatic sealing member 62, the sleeve 46 and into the well bore (notshown) during the drilling operation. Drilling fluid is usuallycirculated downwardly through the inner or central bore of the drillstem to the drill bit 75 for facilitating the drilling of the bore. Thefluid is normally returned from the bottom of the well bore upwardlyaround the drill stem and into the sleeves 46 and 14. The returning orcirculating fluid is discharged from the sleeve 14 through the port 47and is directed through the conduit 5) to the slush pumps (not shown)for recirculation into the bore of the drill stem. The sleeve 36 and thedrill stem are both rotated by the rotary table 54s and thus, there isusually no relative rotation therebetween. The stripper or sealingmember 62 provides a static seal between the sleeve 30 and the drillstem lto preclude any leakage of the fluid upwardly around the drillstem. The sleeve 14 is stationary, as hereinbefore set forth, and thepacking members 36 provide a dynamic seal between the rotating sleeve 30and the stationary sleeve 14. It will be apparent that the combinedstatic and dynamic sealing of the control head f6 substantiallyprecludes any leakage of fluid therethrough during the drilling of awell bore.

The sleeve 46 depending downwardly from the lower portion of the body 12extends into the inner bore of the usual surface string 74 of the wellbore. An annular collar 76 is threadedly secured to the upper portion ofthe surface string 74 by a suitable coupling member 77 and is providedwith a sealing ring 78 disposed in an annular recess Si) on the innerperiphery of the collar 76. The sealing ring '73 is preferably anO-ring, or the like, but not limited thereto, and cooperates with theouter periphery of the sleeve 46 to provide a fluid seal between thesleeve 46 and collar 76 to substantially preclude fluid leakagetherebetween. The sleeve 46 also extends downwardly over the usual wellcasing 82 that is normally concentrically arranged within the surfacestring 74. An annular collar 84 is threadedly secured to the upperportion of the well casing 82 by means of any suitable coupling memberSe', as is well known. An annular sealing ring 36 is disposed within anannular recess 88 provided on the outer periphery of the collar 84. Thesealing ring 86 is in sealing contact with the inner periphery of thesleeve 46 to provide a fluid seal between the collar 64 and the sleeve46 and to substantially preclude fluid leakage therebetween. The surfacestring 74, well casing 82 and coupling member 8S are standard equipmentin well bores and are shown in dotted lines for purposes ofillustration.

Since the well casing 82 is concentrically arranged within the surfacestring 74, an annular cavity 9d is formed between the casing 82 and thesurface string 74. Thus, when it becomes desirable to change the drillbit 75 depending from the drill string 73, the flange 4S is disconnectedfrom the flange 18 so that the sleeve 46 may be lowered with respect tothe body 14. The sleeve 46 is lowered into the cavity 9) until theflange 48 contacts the collar 76. The drill stem is then moved upwardlythrough the control head it? until the drill bit is positionedimmediately below the sealing member 62.. Since the sleeve 46 has beendisconnected from the flange 18 and moved downwardly, the drill bit isreadily accessible for service. However, during-the ordinary drilling ofthe well bore, the seals 86 and 78 cooperate with the stationary sleeve46 to substantially preclude any fluid leakage thereby and to maintain aconstant fluid pressure within the well bore.

Referring to FIG. 3, reference character 92 generally designates amodified control head comprising a substantially tubular body 94. Thetubular body 94y is provided air/ama with an upper outwardly extendingcircumferential llange 96 and a lower outwardly extendingcircumferential liange 9S. The anular flange 98 may be secured directlyto the surface string 74 or it may be secured to the cylinder 46, as setforth in the preferred embodiment, and which is slidably positionedbetween the well casing 82 and the surface string *74, as clearly shownin FIG. l. The cylindrical body 94 is provided with an aperture 106around which a cylindrical element 102 is positioned for a purpose whichhas been hereinbefore set forth. A sleeve 104 having in inwardlydirected flange 166 at one end thereof and an outwardly directed flange108 at the opposite end thereof is positioned on the upper portion ofthe tubular body 94. The circumferential flanges 1&8 and 96 are providedwith a plurality of aligned apertures 110 which may be mated forreceiving any suitable closure members, such as bolts 112.

A plurality of annular chevron sealing members 114, or any othersuitable type of sealing members, such as are well known in the art, arepositioned within the sleeve 104 and held therein by a retaining ring116 threadedly secured to the lower end of the sleeve 164. Lubricationis supplied to the aforesaid sealing members 114 by means of a lubricantfitting 118 disposed in the side wall of the sleeve 104. As has beenhereinbefore set forth, the lubricant is preferably an oil suppliedunder pressure, although any suitable grease may also be employed.

An annular flange 120 is bolted to the underside of the rotatableportion of the rotary table 54 (not shown in FIG. 3) for rotationtherewith. The flange 120 is provided with a particularly configuredrecess 122 for receiving an outwardly extending flange 124 of acylindrical body 126. The recess 122 and llange 124 cooperate to providea substantially bayonet type connection. The flange 124 is preferablyshaped to form a plurality, preferably three, outwardly extending ears127 which cooperate with the particularly configured recess 122 fordisposition therein as is clearly shown in FIG. 4. As shown in FIG. 4,the recess 122 is provided with three upwardly extending slots 128 forreceiving the outwardly extending members 127 as the body 126 is moveddownwardly through the flange 120. After the members 127 of sleeve 126have been positioned within the recess 122, the sleeve 126 is rotatedslightly and locked in position by any suitable means, such as a springbiased locking pin 13b which passes through the flange 126 into alocking position with the flange 124.

During operation of the novel control head 92, the sleeve v126 ispositioned intermediately within the sleeve 104 so that it contacts theseal members 114 which provide a dynamic seal therebetween. Thus, thedynamic seal members 114 substantially preclude the leakage of thecirculating fluid, either liquid or gas, and any cuttings carriedthereby through the point of contact of the rotatable member 126 and thestationary body portion 94. The cylindrical member 126 is provided withan inwardly extending flange 132 for a purpose which will be hereinafterset forth. A sleeve 134 having an inwardly extending llange 136 at theupper portion thereof is disposed below the sleeve 126 and adjacent tothe flange 132 in order that the llange 136 may be secured thereto byany suitable means, such as bolts 137. A static seal between therotatable inner body member and a drilling string passing therethroughis provided by a resilient stripper rubber 140 secured to the lower endsurface of the sleeve 134. A ring 142 is positioned beneath the stripperelement 14@ and secured to the sleeve 134 by bolts 144, or the like, soas to iixedly secure the stripper 140 therebetween. As hereinbefore setforth in the description of the novel control head shown in FIG. l, itis within the scope of the invention to position yet another resilientstripping element (not shown) below the stripper 140 for the purpose ofinitially removing any cuttings carried by the outer periphery of the 5drilling string when it is raised within the stationary body 94 therebymaterially prolonging the active life of the stripper 140.

Operation Assuming that it is desirable to assemble the rotary controlhead 10 so that it will appear as in FIG. 2 for operation, it is iirstnecessary to slip the sleeve 3@ over the lower end of the drill string73 and secure it to the housing 52 whereby the sleeve 3i) may be rotatedsimultaneously with the drill stem bythe rotary table 54. It is assumedthat the sleeve 20 has already been secured to the stationary members 26by any suitable means, such as hooks or hangers, so that the sleeve 3dis initially moved upwardly through the central bore 32 of the sleeve 30before it is secured to the bushing 52. The sleeve 46 is then moveddownwardly within the cavity between the well casing 82 and the surfacestring 74 until the flange 4g abuts the collar 76 connected to the upperportion of the surface string 74. The tubular body 14 is then movedupwardly over the lower portion of the drill stem into a positionwherein its integral flange 16 may be secured to flange 22 of the sleevebody 2l) in any suitable manner, such as vby the lugs 21 or by athreaded connection (not shown). It will be apparent that the drill bit75 may be secured to the lower end of the drill stem since the sleeve 46is in the lowered position for providing access to the drill stern. Thesleeve 46 is then moved upwardly within the cavity 90 and secured to theflange 18 of the body 14 in a manner similar to that utilized in theconnection of flanges 22 and 16. However, it is understood that it maybe desirable to have different means of connecting the flanges 16 and 18to their respective members so that the invention is not limited to theuse of the same connecting means in both instances. The drill bit 75 isthen moved downwardly within the sleeve 46 into the well casing 82 forthe drilling of the well bore.

As the drill string is rotated within the well bore by the rotary table54, the sleeve 30 is simultaneously rotated therewith so that there isno relative rotation between the circular seal member 62 and the drillstring. The bore extending through the sealing member 62 closely litsthe outer periphery of the drill string so that there is susbtantiallyno liuid leakage therebetween, regardless of whether the circulatingfluid being utilized is either liquid or air. Thus, the novel rotarycontrol head provides an eiiicient static seal between the rotatingdrill pipe and the rotating portion of the control head.

The packing or chevron seals 36 disposed in the annular cavity formedbetween the sleeve 20 and the sleeve 30 are in sealing contact with theouter periphery of the sleeve 39 as it is rotated with the drill string,thus providing an eliicient dynamic seal between the rotating sleeve 3?and stationary sleeve 26 whereby leakage of the circulating uidtherebetween may be substantially precluded.

The packing or O-ring 8i) that is carried by the collar 76 secured tothe surface string 74 also contacts the outer periphery of the sleeve 46in sealing position. The packing or O-ring 86 that is carired by thecollar 88 connected to the upper portion of the well easing 82 alsocooperates with the inner periphery of the sleeve 46 to provide a sealtherebetween and to substantially preclude iiuid leakage. Thus, thecirculating fluid present in the well bore is precluded from leakagepast the point of contact of the sleeve 46 with the collars of thesurface string and the well casing by the cooperation of the seals 81Band 86 with the sleeve 46. If the ordinary form of fluid circulation isutilized, the fluid passes downwardly through the drill string and thenmoves upwardly around the drill string and through the well casing 82until it passes through the aperture 47 in the body 14 of the controlhead 10 and into the tube 5t) for recirculation through the well bore.

When it is necessary to replace the drill bit, the drill string ispulled or moved upwardly within the well bore until the drill bit isadjacent to and spaced directly below the sealing member 62 carried bythe sleeve 56. As the drill string is moved upwardly within the wellbore, the seal member 62 exes upwardly around the outer periphery of thedrill strinfT so that `any possibility of rupturing or tearing of theseal member 62 by the string as it is pulled upwardly therethrough maybe materially reduced. The fluid circulation is, of course, haltedduring this period so that the control head is free of any circulatinguid. When the drill bit is positioned below the sealing member 62, theange 43 of the sleeve 46 is then disengaged from its connection with thellange 18 of the body 14 by removing the bolts or other securing meansused to secure the two flanges 18 and i3 together. The sleeve 46 is thenmoved downwardly within the annular space 90 between the surface string74 and the well casing 82 until the ilange 48 iabuts the upstandingcollar secured to the upper portion of the surface string 74. The drillbit is then positioned between the lower portion of the tubular body 14and the flange-d portion 48 of the sleeve 46 so that it may be readilyserviced or replaced as the circumstances may require. The control headmay be partially disassembled while in place for service or removal ofthe drill bit `and also provides elicient sealing of the rotating drillstem without the necessity of cornpletely removing or disassembling thecontr-ol head when it is necessary to remove the drill bit.

The operation of the modilication of the novel rotary control head shownin FlGS. 3 and 4 is substantially similar to the operation of thepreferred form of the invention as hereinbefore set forth. The ilange120 is initially bolted or otherwise secured to the bottom of the rotarytable before the sleeve 126 is moved downwardly within the rotary tableand secured to flange 120 by a locking means, such as pin 130, engagingthe ear 127 of the sleeve 126. The body portion 94 is assembled andpositioned below the flange 12() so that when the sleeve 126 is moveddownwardly within the flange 120, it will pass through the sleeve 1&4carrying the packing members 114 and establish a sealing contacttherewith. The body portion 94 may be secured in any well known manner(not shown) to the surface string or a blow-out preventer (not shown)which may be selectively positioned therebelow. Prior to the locking ofsleeve 126 in flange 120, a portion of a drill string is passed throughthe stripper rubber 140 so that a suitable drill bit may be secured tothe bottom portion thereof. The drill bit is chosen so that its greatestdiameter is no greater than the diameter of the sleeve 126, therebyallowing the drill string with the depending drill to be withdrawn fromthe control head with the sleeve 125.

When the drill bit becomes worn or it is otherwise necessary to serviceit, the locking means 130 is moved to allow the ears 127 of the sleeve126 to be rotated into position so that the sleeve 126 `and the drillstring passing therethrough may be moved upwardly. Since the drill bitis of less diameter than the sleeve 126, it may be withdrawn with thesleeve through the dynamic seal 114 and the flange 126 to the surface ofthe rotary table where it may be replaced or serviced. As in the formor" the invention shown in FlGS. 1 and 2, the seal members 114 furnish adynamic seal between the stationary and the rotating portions of thecontrol head and the stripper rubber 140 furnishes a static seal betweenthe drill string and the rotating portion of the control head. In themodiiication of the invention shown in FGS. 3 and 4, the rotatingportion is removed from contact with the stationary body portion,whereas in FIGS. l and 2, the invention shown therein has the stationaryportion of the invention lowered from contact with the rotating portionfor service of the drill bit.

From the foregoing, it is apparent that the present invention provides anovel rotary control head that elliciently packs off a rotating drillstring from the well casing and substantially precludes any leak-age ofthe circulating fluid by furnishing a dynamic seal between the rotatingand non-rotating portions of the control head and a static seal betweenthe drill string and the head portion rotating simultaneously therewith.It is also apparent that the novel control head may be partiallydisassembled quickly to allow service of the drill bit withoutcompletely disassembling the control head and the attendant structure.The subject control head is ellicient in operation, simple and economicin construction, and exible in use that it may be employed inlapplications wherein liquid mud and air are used interchangeably.

Changes may be made in the combination and arrangernent of parts asheretofore set forth in the specification and `shown in the drawings, itbeing understood that any modification in the precise embodiment of theinvention may be made within the scope of the following claims withoutdeparting from the spirit of the invention.

I claim:

1. A rotary control head for a drill string and cornprising a stationarybody member, a sleeve member extending into the body member androtatable with the drill string, static seal means interposed betweenthe sleeve and the drill string, dynamic seal means interposed betweenthe stationary body and the sleeve, passageway means for discharge oflluid from the control head, a pair of concentric annular collars having`an annular space therebetween and spaced from the stationary body, asleeve member removably secured to the Ilower end of the stationary bodyand reciprocally disposed in the annular space between the collars toprovide for access to the drill string without a complete disassembly ofthe control head, seal means interposed between the movable sleeve andthe collars for precluding leakage of fluid therebetween, and meansprovided for limiting the downward reciprocal movement of the removablesleeve.

2. A rotary control head for a drill string and comprising a stationarybody member, a rotatable sleeve disposed around the dril-l string andextending into the body member, static seal means interposed between theSleeve and the drill string, dynamic `seal means interposed between thestationary body and the rotatable sleeve, passageway means for dischargeof fluid from the control head, a pair of concentric annular collarshaving an annular space therebetween and spaced from the stationarybody, a sleeve member removably secured to the lower end of thestationary body and reciprocally disposed within the annular space toprovide for access to the drill string without la complete disassemblyof the control head, means provided for limiting the downward reciprocalmovement of the removable sleeve, and seal means precluding leakage or^lluid between the collars and the removable sleeve.

3. A rotary control head for a drill string, and comprising a stationarybody member, a sleeve concentrically disposed Within the body member androtatable with the drill string, static seal means interposed betweenthe rotatable sleeve and the drill string, dynamic seal means interposedbetween the stationary body and the rotatable sleeve, a pair ofconcentric collars having an annular space therebetween and spaced fromthe stationary body, a second sleeve removably secured to the lower endof the stationary body and in substantial alignment with the rotatablesleeve for receiving the drill string therethrough, said second sleeveextending into the annular space and reciprocal with with respect to thestationary body and collars to permit access to the drill string withouta cornplete disassembly of the control head, means provided for limitingthe downward reciprocal movement of the removable sleeve, seal means topreclude leakage of uid between the removable sleeve `and the collars,and passageway means for discharge of fluid from the control head.

4. In `combination with a well casing, and a drill string, a rotarycontrol head comprising a stationary body member, a sleeve disposedaround the drill string and rotatable therewith, static seal meansinterposed between the sleeve and the drill string, dynamic seal meansinterposed between the stationary body land the rotatable sleeve,prassageway means `for discharge of lluid from the control head, a`sleeve member removably secured to the lower end of the stationary bodyand reciprocally disposed within 'an annular space surrounding the wellcasing to permit access to the drill string without a completedisassembly of the control head, means provided for limiting thedownward reciprocal movement of the removable sleeve around the wellcasing, and seal means interposed between the reciprocal sleeve and thewell casing.

5. In combination with a well casing and a drill string, a rotarycontrol Ihead comprising a stationary body member for receiving thedrill string therethrough, .a sleeve concentrically disposed within thebody member and around the drill string, said sleeve rotatablesimultaneously with the drill string, static seal means carried by thesleeve for precluding leakage of fluid around the drill string, dynamicseal means carried by the stationary body member for precluding leakageof uid around the rotatable sleeve, a second sleeve removably secured tothe stationary body for receiving the drill string therethrough, saidsecond sleeve extending downwardly in an annular Space surrounding thewell casing and reciprocal therein upon disconnection from thestationary body to permit access to the drill `string without a completedisassembly of the control head, means provided for Ilimiting thedownward reciprocal movement of the said second sleeve, and seal meanscooperating between the well casing and the reciprocal sleeve topreclude leakage of uid therebetween, and passageway means for dischargeof iluid from the control head.

References Cited in the le of this patent UNITED STATES PATENTS1,503,476 Childs et al Aug. 5, 1924 2,199,733 Beckman May 7, 19402,199,734 Beckman May 7, 1940 2,222,082 Leman et al Nov. 19, 19402,243,340 Hild May 27, 1941 2,475,429 Humason July 5, 1949 2,927,774Ormsby Mar. 8, 1960 3,052,300 Hampton Sept. 4, 1962

2. A ROTARY CONTROL HEAD FOR A DRILL STRING AND COMPRISING A STATIONARYBODY MEMBER, A ROTATABLE SLEEVE DISPOSED AROUND THE DRILL STRING ANDEXTENDING INTO THE BODY MEMBER, STATIC SEAL MEANS INTERPOSED BETWEEN THESLEEVE AND THE DRILL STRING, DYNAMIC SEAL MEANS INTERPOSED BETWEEN THESTATIONARY BODY AND THE ROTATABLE SLEEVE, PASSAGEWAY MEANS FOR DISCHARGEOF FLUID FROM THE CONTROL HEAD, A PAIR OF CONCENTRIC ANNULAR COLLARSHAVING AN ANNULAR SPACE THEREBETWEEN AND SPACED FROM THE STATIONARYBODY, A SLEEVE MEMBE REMOVABLY SECURED TO THE LOWER END OF THESTATIONARY BODY AND RECIPROCALLY DISPOSED WITHIN THE ANNULAR SPACE TOPROVIDE FOR ACCESS TO THE DRILL STRING WITHOUT A COMPLETE DISASSEMBLY OFTHE CONTROL HEAD, MEANS PROVIDED FOR LIMITING THE DOWNWARD RECIPROCALMOVEMENT OF THE REMOVABLE SLEEVE, ADN SEAL MEANS PRECLUDING LEAKAGE OFFLUID BETWEEN THE COLLARS AND THE REMOVABLE SLEEVE.